Treadle scooters have been in use throughout the world for many years and come in a variety of styles. Broadly speaking, a treadle scooter includes a platform (commonly known as a rocker board) that is pivotally attached to a frame and a drive force is provided to a wheel rotatably attached to the frame through a drive train by a user pivoting the platform relative to the frame using his or her feet.
FIG. 1 illustrates a particular form of a prior art treadle scooter 10. The treadle scooter 10 consists of a frame 12 in the form of a simple truss formed by first and second inclined segments 14, 16 connected at their proximal ends with their distal ends joined by a horizontal member 18. The frame 12 of the prior art treadle scooter 10 further consists of a forward member 20. A first wheel 22 is rotatably mounted to a first or front end of the frame 12 at a distal end of the forward member 20. A second wheel 24 is rotatably mounted to a second or rear end of the frame 12 between a pair of stays 16a, 16b, which form the inclined member 16, by an axle 25. More particularly, the first wheel is attached to first end of the frame by means of a head tube 26 that is attached to the distal end of the forward member 20 and receives a steering shaft 28 having a handle bar 30 at its top end. A front fork 32 is attached to a bottom end of the steering shaft 28 and the first wheel 22 is received between opposing legs of the front fork 32 and rotatably attached to the front fork 32 by the axle 34.
In the prior art treadle scooter 10, a drive train 36 is provided to drive rotation of the second wheel 24. The drive train 36 consists of a rocker board 38 which is pivotally attached to the frame 12 at an apex of the inclined segments 14, 16 by a hinge 40 (see FIG. 2). The rocker board 38 consists of a first or front portion 42 and a second or rear portion 44 on opposite sides of the hinge 40. The hinge 40 is located at the lengthwise center of the rocker board 38. The top surface of the first portion 42 and the top surface of the second portion 44 of the rocker board 38 are configured to receive a first and second foot of a user operating the prior art treadle scooter 10. A first one-way clutch 46 is operatively associated with a right side of the second wheel 24 to rotate the second wheel 24 in a drive direction when an actuation pulley 48 fixedly attached to the one-way clutch 46 is rotated in a first direction and to allow free rotation or “freewheeling” of the second wheel when the actuation pulley attached to the first one-way clutch 46 as rotated in a second direction Likewise, a second one-way clutch 50 is operatively associated with the left side of the second wheel 24 to rotate the second wheel 24 in a drive direction when an actuation pulley 52 attached to the second one-way clutch 50 is rotated in a first direction and to allow free rotation of the second wheel 24 when the actuation pulley 52 attached to the second one-way clutch 50 is rotated in a second direction. A guide pulley 54 is rotatably mounted to the frame 12 proximate the front end of the frame 12 and more particularly on the inclined segment 14 and is operatively aligned with the actuation pulley 48 attached to the first one-way clutch 46 to direct a drive line 56 between the guide pulley 54 and the actuation pulley 48. A tensioning pulley 58 is attached by a tensioning spring 60 in the form of a coil spring to the frame proximate the first end of the frame. The drive line 56 is attached at a first end 62 to a bottom of the rocker board 38 proximate a distal end of the front portion 42. The drive line 56 thereafter is wrapped approximately 90° around the guide pulley 54 and approximately 180° around the actuation pulley 48 attached to the first one-way clutch 46. The drive line 56 continues by wrapping 180° around the tensioning pulley 58 and then approximately 90° around the actuation pulley 52 attached to the second one-way clutch 50 and the second end 64 of the drive line 56 is attached to the bottom of the rocker board 38 proximate a distal end of the second end 44 of the rocker board 38. In the prior art embodiment illustrated in FIG. 2, the drive line 56 includes a first chain segment 66 extending between the first end 62 and around the guide pulley 54 and the actuation pulley 48 attached to the first one-way clutch 46 and a second chain segment 68 extending between the second end 64 and the actuation pulley 52 attached to the second one-way clutch 50 and an intermediate cable portion 70 between the first and second chain segments 66, 68 extending around the tensioning pulley 58. In this embodiment the guide pulley 54 and both the actuation pulleys 48, 52 each have radially extending teeth configured to engage the lengths of the respective first and second chain segments in a manner well known in the art. Other embodiments could consist of the drive line 56 being a cable with the teeth of the guide pulley 54 and the actuation pulleys 48, 52 being replaced with a circumferential groove.
Referring to FIG. 3, in use, when the rocker board 38 is actuated by a user to lower the second or rear end 44 of the rocker board, the first or front end 42 of the rocker board and the associated second end of the drive line 62 is pulled upward rotating the actuation pulley 48 and the attached first one-way clutch 46 in the first direction, thereby rotating the second wheel in the drive direction, and rotating the actuation pulley 52 and the attached second one-way clutch 50 in the second direction, allowing free rotation of the second wheel. Referring to FIG. 4, when the rocker board 38 is actuated by the user to lower the first end 42 of the rocker board 38, the second end 44 of the rocker board 38 and associated second end 64 of the drive line 56 is pulled upward rotating the actuation pulley 52 and the attached second locking roller clutch 50 in the first direction, thereby rotating the second wheel 24 in the drive direction and rotating the actuation pulley 48 and the attached first one-way clutch 46 in the second direction, allowing free rotation of the second wheel 24. With no pivoting of the rocker board 38, neither the first nor the second one-way clutches are engaged in the first direction, leaving the second wheel free to rotate in the drive direction
One form of one-way clutches known in the art are ratchet clutches 71 schematically illustrated in FIG. 5 consisting of a first ring shaped outwardly extending flange 72 having a plurality of teeth shaped recesses 73 extending around an internal recess of the flange 72. A number of ratchets or fingers 74 are provided (one shown in FIG. 5 for simplicity) which are spring-biased (spring not shown) outwardly to engage the tooth shaped recesses 73 and are shaped and oriented so that the ratchet 71 can freely rotate in one direction 75 but is prevented from rotating in the opposite direction since the fingers are biased to engage the recesses. Such a ratchet structure is described in greater detail in U.S. Pat. No. 7,914,027, the content of which is expressly incorporated by reference herein. Such one-way ratchet clutches have a backlash equal to the ratchet tooth spacing which inhibits immediate actuation of a drive force in use. In addition, such one-way ratchet clutches make a clicking sound when free-wheeling. Furthermore, such one-way ratchet clutches suffer wear during free-wheeling.
A preferred one-way clutch is a locking roller clutch which could include a conventional locking roller clutch 76 shown schematically in FIG. 6 with rollers 77 residing in an outer casing 78 spring biased (spring not shown) to drive up ramps 79 associated with a shaft 80 within the locking roller clutch 76 or locking needle roller clutch 76a shown schematically in FIG. 5 having ramps 79a in an outer casing 78a and rollers 77a directly contacting a shaft 80a or hub residing within the outer casing 78a that are spring-biased (spring not shown) up the ramps 79a. Either form of locking roller clutch provides near instantaneous rotational drive when rotated in a drive direction, is silent when freewheeling and experiences little wear when freewheeling. However, in use, locker roller clutches deployed in a prior art treadle scooter 10 as depicted in FIGS. 1-4 require slightly less chain pull on the left side of the drive train and greater force to be applied to the front of the rocker board 38 in order to drive the second locking roller clutch 50.
The present invention is directed toward overcoming one or more of the problems with prior art treadle scooter drive trains using locking roller clutches.